Doctor roll with spiral grooves



April 4, 1967 D. v. LOWE 3,312,191

DOCTOR ROLL WITH SPIRAL GROOVES Original Filed April 8, 1965 2 Sheets-Sheet 1 IN VE N TOR.

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ATTORNE Y8 April 4,1967 D. v. LOWE 3,312,191

' DOCTOR ROLL WITH SPIRAL GROOVES Original Filed April 8, 1965 2 Sheets-Sheet z INVE'NTOR 42 .DONALO I- Law! BY xmdyl z ATTORNEYS United States Patent Ofiice 3,312,191 Patented Apr. 4, 1967 3,312,191 DUCTOR ROLL WITH SPIRAL GROOVES Donald V. Lowe, Tenafly, NJ., assignor to Lowe Paper Company, Ridgefield, N J a corporation of New Jersey Continuation of application Ser. No. 453,862, Apr. 8, 1965. This application May 13, 1966, Ser. No. 555,927 3 Claims. (Cl. 118104) This is a continuation of application Ser. No. 453,862 filed Apr. 8, 1965, and a continuation-in-part of application Ser. No. 337,390, filed Jan. 13, 1964, both now abandoned.

The present invention relates to coating apparatus and in particular to a device for removing dirt particles or foreign matter which accumulate between the nip of the doctor roller component of the coating machine apparatus and the coated paper web.

In apparatus which utilize the reverse roll process to apply coatings to moving webs, one of the major problems is the formation of streaks resulting from dirt particles or foreign matter which accumulate between the nip of the doctor roller and the paper web.

It is, therefore, an object of this invention to provide an improved coating machine.

It is another object of this invention to provide a device to prevent dirt particles or foreign matter from accumulating between the nip of the doctor roller and the coated paper web.

Accordingly, the outer surface of a doctor roller is provided with a plurality of passages, whereby when the roller is rotated, any dirt particles or foreign matter located On the outer surface or nip of the roller would be forced into these passages by the pressure of the doctor blade against the roller surface. The natural hydraulic flow of the coating fluid induced by the motion of the passages together wit-h the viscosity of the coating fluid itself will cause the dirt particles or foreign matter to become suspended in the coating fluid and pushed out of the roller at its lateral edges, thereby eliminating the possibility of streaks being formed on the paper being coated.

Further features and advantages of the invention will become apparent from the following detailed specification, with reference being had to the drawing, wherein:

FIG. 1 is a schematic elevational sectional view of an apparatus for applying coatings to moving webs by the reverse roll process;

FIG. 2 is a section taken along line 2-2 of FIG. 1, showing one embodiment of the device for carrying out the novel method according to the invention;

FIG. 3 is a similar view of another embodiment of the invention;

FIG. 4 is a fragmentary cross-section taken along line 44 of FIG. 2;

FIG. 5 is a fragmentary cross-section taken along line 55 of FIG. 2; and

FIGS. 6-9 respectively illustrate additional embodiments of doctor rollers according to the present invention.

Referring now in more detail to the drawing wherein similar reference numerals identify corresponding parts throughout the several views, 10 represents a reverse roll apparatus for removing an excess layer of coating from a moving paper web, substantially as shown. A rotating doctor roller 12 is placed in close proximity to the moving paper web 14 to remove any excess coating. A doctor blade 16 is held against the face 18 of the doctor roller and adapted to remove the excess coating which has adhered to the roller and at the same time force any remaining coating and/or, dirt 20 into the spiral grooves 22 cut into the outer surface 18 of the doctor roller 12.

According to the invention these grooves 22 in conjunction with the rotation of the doctor roller 12 provide a sort of downhill channel along which a stream of coating fluid will flow, carrying with it the dirt particles or foreign matter that had been forced into the grooves 22 by the action of the doctor blade 16. This stream of coating fluid flowing in the grooves 22 is transported by the motion of the spiral cut grooves 22 to the lateral edges of the doctor roller 12 and then out of the apparatus.

It is to be understood that instead of the grooves 22 shown in FIG. 2, other configurations of grooves may be provided, such as the grooves 24 shown in FIG. 3.

While FIGS. 2 and 3 show spiral grooves, the passages which are formed in the exterior surface of the doctor roller can take widely different forms. Thus, FIG. 6 shows a doctor roller 30 which may be used instead of the roller 12 and which has relatively small axially extending grooves 32 extending all the way along the roller 30. FIG. 7 shows a doctor roller 34 which can replace the roller 12 and which has somewhat larger axially extending grooves 36 which extend along the roller 34 and have open ends situated at the ends of the roller 34. FIG. 8 shows a doctor roller 38 which can replace the roller 12 and which has spiral grooves similar to the grooves 24 of FIG. 3 except that they have a much larger pitch so that the solution of FIG. 8 is between that of FIG. 3 and that of FIG. 7.

FIG. 9 shows a roller 40 which can be used to replace the roller 12, and this roller 40 has been sand blasted at its exterior surface so as to be provided with a large number of pits 42. These pits 42 all communicate with each other and form haphazardly extending passages directed in all directions with respect to the roller 40 so that when the blade 16 presses the coating 20 against the surface of the roller 40, the material of the coating 20 will also flow to the ends of the roller 40 along the passages which have their directions haphazardly determined by the pits 42.

Thus it will be seen that with the structure of the invention the rotary doctor roller is adapted to engage the coated web 14 and to rotate in a direction which displaces the surface of the roller which engages the web in a direction opposite to the direction of movement of the web so that the roller removes excess coating material from the moving web, and this excess coating material is indicated at 20 in FIG. 4. The roller of the invention is provided with passages which are circumferentially distributed about the roller and which extend towards the ends of the roller, and these passages have open ends which are situated at the ends of the roller. The doctor blade 16 extends longitudinally of and engages the roller at a given line along its exterior surface, and this blade 16 has a lower surface, as viewed in FIG. 4, directed toward the roller and forming an acute angle with a plane which is tangent to the roller at the line of engagement between the blade and the roller. Of course, the blade 16 also has an upper surface, as viewed in FIG. 4, directed away from the roller and forming an obtuse angle with the tangent plane, and the direction of the rotation of the roller will advance the surface thereof toward the line of engagement at the side of the blade which forms an acute angle between the tangent plane and the surface of the blade which is directed toward the roller, so that in this way during rotation of the roller the blade will necessarily press into the passages of the roller any excess coating on the roller, and this excess coating will necessarily flow along the passages out of the latter at the open ends thereof which are situated at the ends of the roller, so that any particles of dirt or other foreign matter will be displaced with the excess coating away from the roller so as to prevent streaking of the web.

What I claim is:

1. In an apparatus for coating a web of sheet material, a rotary doctor roller adapted to engage the coated web and to rotate in a direction which displaces the surface of the roller which engages said web in a direction opposite to the direction of movement of the web so that said roller is adapted to remove excess coating material and foreign particles such as dirt from the moving web, said roller being for-med at its exterior surface with a plurality of passages distributed about its circumference and extending from one end of the roller to the other end thereof forming openings respectively situated at the opposite ends of the roller, and an elongated doctor blade extending longitudinally of and engaging said roller at a given line along its exterior surface, said blade having a surface directed toward said roller and forming an acute angle with a plane tangent to said roller at the line of engagement between said blade and roller, the direction of rotation of said roller advancing the surface thereof toward the line of engagement at the side of said blade which forms an acute angle between said plane and the surface of said blade which is directed toward said roller,

said passages being formed such that the path of any given passage while being traced during rotation of said roller in the area of said web travels less than 360 from the point of engagement thereof with the blade to the subsequent point of engagement with said web, whereby during rotation of said roller said blade will press into said passages any excess coating on said roller and the excess coating will flow along said passages out of the latter at the said openings situated at the ends of said roller, so that any particles of dirt or foreign matter will be displaced with the excess coating along said passages and away from said roller to prevent streaking of the web.

2. In an apparatus as recited in claim 1, said passages extend spirally along the exterior surface of said roller along the complete axial extent thereof.

3. -In an apparatus for coating a web of sheet material as recited in claim 1, wherein each of said passages originate substantially intermediate between the ends of said roller and extending to the ends thereof, and each of said passages communicate with an opposite passage at a portion intermediate between the ends of said roller, the arrangement being such that during rotation first the intermediate portion of each passage comes into engagement with said blade.

References Cited by the Examiner UNITED STATES PATENTS 1,235,326 7/1917 Kinsley 118261 1,243,808 10/ 1917 Cafr'rey 111424 XR 1,575,868 3/1926 Roles 118-102 1,826,801 10/1931 Littleford.

1,867,875 7/1932 Buchanan 118-119 1,955,414 4/1934 Dickhaut 118-118 2,176,835 10/ 1939 Cumfer.

2,249,088 7/ 1941 Murray 117-64 2,513,394 7/1950 Barrett et a1. 118262 X 2,558,773 7/1951 Mulloy et al 1l8l01 2,598,733 6/1952 Warner 1l8104 2,599,947 6/ 1952 Sherman et al. 118-104 2,605,684 8/1952 Nagels et al. 118-2s2 X 2,714,365 8/ 1955 Rowlands 118262 2,874,674 2/1959 Hornbostel 118104 3,176,649 4/ 1965 Heiseler 118261 3,194,210 7/1965 Harris 118-104 MORRIS KAPLAN, Primary Examiner. 

1. IN AN APPARATUS FOR COATING A WEB OF SHEET MATERIAL, A ROTARY DOCTOR ROLLER ADAPTED TO ENGAGE THE COATED WEB AND TO ROTATE IN A DIRECTION WHICH DISPLACES THE SURFACE OF THE ROLLER WHICH ENGAGES SAID WEB IN A DIRECTION OPPOSITE TO THE DIRECTION OF MOVEMENT OF THE WEB SO THAT SAID ROLLER IS ADAPTED TO REMOVE EXCESS COATING MATERIAL AND FOREIGN PARTICLES SUCH AS DIRT FROM THE MOVING WEB, SAID ROLLER BEING FORMED AT ITS EXTERIOR SURFACE WITH A PLURALITY OF PASSAGES DISTRIBUTED ABOUT ITS CIRCUMFERENCE AND EXTENDING FROM ONE END OF THE ROLLER TO THE OTHER END THEREOF FORMING OPENINGS RESPECTIVELY SITUATED AT THE OPPOSITE ENDS OF THE ROLLER, AND AN ELONGATED DOCTOR BLADE EXTENDING LONGITUDINALLY OF AND ENGAGING SAID ROLLER AT A GIVEN LINE ALONG ITS EXTERIOR SURFACE, SAID BLADE HAVING A SURFACE DIRECTED TOWARD SAID ROLLER AND FORMING AN ACUTE ANGLE WITH A PLANE TANGENT TO SAID ROLLER AT THE LINE OF ENGAGEMENT BETWEEN SAID BLADE AND ROLLER, THE DIRECTION OF ROTATION OF SAID ROLLER ADVANCING THE SURFACE THEREOF TOWARD THE LINE OF ENGAGEMENT AT THE SIDE OF SAID BLADE WHICH FORMS AN ACUTE ANGLE BETWEEN SAID PLANE AND THE SURFACE OF SAID BLADE WHICH IS DIRECTED TOWARD SAID ROLLER, SAID PASSAGES BEING FORMED SUCH THAT THE PATH OF ANY GIVEN PASSAGE WHILE BEING TRACED DURING ROTATION OF SAID ROLLER IN THE AREA OF SAID WEB TRAVELS LESS THAN 360* FROM THE POINT OF ENGAGEMENT THEREOF WITH THE BLADE TO THE SUBSEQUENT POINT OF ENGAGEMENT WITH SAID WEB, WHEREBY DURING ROTATION OF SAID ROLLER SAID BLADE WILL PRESS INTO SAID PASSAGES ANY EXCESS COATING ON SAID ROLLER AND THE EXCESS COATING WILL FLOW ALONG SAID PASSAGES OUT OF THE LATTER AT THE SAID OPENINGS SITUATED AT THE ENDS OF SAID ROLLER, SO THAT ANY PARTICLES OF DIRT OR FOREIGN MATTER WILL BE DISPLACED WITH THE EXCESS COATING ALONG SAID PASSAGES AND AWAY FROM SAID ROLLER TO PREVENT STREAKING OF THE WEB. 